Conventionally, a rehabilitating operation of a pipe line is widely performed, the operation helically winding a long profile strip to form a rehabilitating pipe, and laying the rehabilitating pipe in a deteriorated existing pipe. Generally, the profile strip includes a plurality of ribs continuously disposed along the longitudinal direction, and in some cases, a metal reinforcing material is attached between the ribs. Since the profile strip to which the reinforcing material is attached has a high rigidity, it is suitably used for forming the rehabilitating pipe having a high self-supporting strength. This kind of profile strip is wound in a state in which the reinforcing material is attached in advance so as to be transported to a construction site.
At the time of construction, the reinforcing material-attached profile strip, which is wound on a drum for construction, is drawn. Thus, the profile strip has curls when it is being wound on the drum. Such curls of the profile strip have different curvatures depending on where the profile strip is wound, i.e., on the inner peripheral side or on the outer peripheral side of the drum. Accordingly, the curvature changes gradually as the profile strip is drawn from the drum to form the rehabilitating pipe. Thus, the profile strip may get stuck with the inner wall of the manhole at the construction site when it is introduced from the manhole. Also, when the rehabilitating pipe with a radius of curvature smaller than that of the profile strip is formed, there is another problem that it is difficult to form the rehabilitating pipe having a target pipe diameter because the diameter of the rehabilitating pipe gradually increases due to a restoring force to allow the profile strip to restore to its original radius of curvature.
In order to resolve the above conventional problems, the Applicant of the present invention has proposed an apparatus for forming curls (hereinafter referred to as a curl-forming apparatus) for deforming the profile strip before the production of the pipe so that the profile strip has a desired helical shape, as disclosed in patent Document 1.